vba New Objects 2007/2010

Does anyone know why this only runs in ThisDocument class and not a module?

Has anyone used these new objects? Many thanks.

Set fnd = content.Find

Option Explicit
' Word 2010
' Demonstrate some of the features new to the Find object starting in Word 2007:
' IgnorePunct
' IgnoreSpace
' MatchPrefix
' MatchSuffix
' ClearHitHighlight
' HitHighlight
' In a new document, type the following text and then press Enter:
'
' =rand(5, 5)
'
' This action inserts 5 paragraphs with 5 sentences each into the
' current document. Then, in the VBA editor, in the ThisDocument class,
' copy in this code, and place the cursor within
' this procedure and press F8 to single step through the code. Arrange
' the VBA and Word windows side by side on screen so you can view the
' behavior as you step through the code.
Sub DemoFind()
' Set up a search, in the random text, for
' "tab Most"
Dim fnd As Find

' Now clear the highlighting. This is only meaningful
' if you are single-stepping through the code.
fnd.ClearHitHighlight

' Match the text "th" only when it appears at the beginning
' of a word:
fnd.MatchPrefix = True
fnd.text = "th"
fnd.HitHighlight fnd.text, vbYellow, vbRed
' Now clear the highlighting. This is only meaningful
' if you are single-stepping through the code.
fnd.ClearHitHighlight
' Match the text "th" only when it appears at the end
' of a word:
fnd.MatchPrefix = False
fnd.MatchSuffix = True
fnd.text = "th"
fnd.HitHighlight fnd.text, vbYellow, vbRed
' Now clear the highlighting. This is only meaningful
' if you are single-stepping through the code.
fnd.ClearHitHighlight
End Sub